The Research Of The OFDM Baseband Transfer System Based On IEEE802.11a And The FPGA Implementation Of Parts Of Its Modules

OFDM (Orthogonal Frequency Division Multiplexing) technology, due to its longersymbol duration which is resistant to multipath e?ects, has been widely used in many ad-vanced digital communication systems such as IEEE802 wireless family, which has broughthuge impacts and great convenients on human's life and now reaches or is capable of reach-ing virtually every location on the face of the earth. In this case, how to realize e?cientOFDM system has been a very important issue for either academic or industrial fields.Meanwhile, the development of the VLSI and EDA has also made the implementation ofthe OFDM system become possible and feasible.In this thesis, a prototype design for the Physical Layer of IEEE 802.11a standard,which is based on OFDM technique, is presented. Implementation aspects of parts of thefunctional modules of the OFDM system on Xilinx Virtex-II field programmable gate array(FPGA) are addressed. The whole design is accompanied with the top-down strategy, whichhas been the proposed"solution"in FPGA design.The design ?ow starts with ?oating-point modeling with parameters specified by IEEE802.11a for the physical layer. After that, the designs of function models including scram-bler, convolutioner, interleaver, symbol mapper, and pilot insertion are given, which aremainly implemented through ping-pong architecture, Dual-Port RAM and pipelining. Con-sequently, di?erent symbol timing schemes are examined and as the result of the comparison,a modified algorithm based on the multiplierless correlation of received long preamble sym-bols is selected for hardware implementation. Furthermore, the (2,1,6) 4-bit soft-decisionViterbi decoder for QPSK is discussed according to the IEEE802.11a standard. Finally,the hardware scheme and PCB of the FPGA kernel board based on System ACE strategyis given, which makes the FPGA configuration more ?exible.As the OFDM technology becomes more and more widely applied and prevalent, thisthesis demonstrates good reference value in some extent.